The present invention relates to a silicone composition with controlled rheological properties and a specific gravity that varies anywhere from 1.035 to 1.06 and more particularly the present invention relates to silicone compositions with controlled rheological properties and a specific gravity that varies from 1.035 to 1.06 which composition may be utilized in blood serum separation techniques.
Silicone compositions comprising a diorganopolysiloxane fluid and silica filler are well known. For instance, see U.S. Pat. Nos. of John H. Wright - 3,037,933, 3,103,491, 3,145,175, 3,197,319, 3,197,728, 3,304,259, 3,453,210, 3,537,997, 3,671,429, 3,664,953, 3,669,884, 3,473,089, 3,882,033, 3,885,984 and 3,915,924. The silica filler is incorporated into the diorganopolysiloxane fluid as a thickening agent to produce a silicone grease or a channel sealant. Various additives are added to such compositions for one purpose or another. However, the full extent of the properties and uses of such compositions and specifically the full extent of specific compositions within the broad disclosures of the above patents was not appreciated.
Recently, it has become highly desirable to produce a silicone composition with controlled rheological properties and a controlled specific gravity which will allow materials with a higher specific gravity than the silicone composition to pass therethrough and separate from compositions with a lighter specific gravity than the silicone composition. It is desired that such silicone compositions form an integral layer separating the low specific gravity material from the high specific gravity material. Such composition would strongly facilitate the separation of low specific gravity from high specific gravity material.
One of the reasons why a silicone composition was envisioned for such a particular use was because many silicones are basically inert to other reactive materials and also tend to be non-toxic. Accordingly, such a silicone composition has been desired for a clean and efficient separation of a high specific gravity fluid from a low specific gravity fluid. One particular specific application where such a silicone composition was desired was in the analysis of human and animal blood samples. Normally, such blood samples are taken and there may be added to them a catalytic ingredient which will coagulate in the blood sample the undesirable material from the blood serum which is to be utilized for medical analysis. The undesirable material will then be allowed to settle and separate out from the blood serum. However, this procedure left something to be desired in that some of the undesirable blood clotting material was usually present or found in the blood serum that was poured out, irrespective of how careful the separation procedure was carried out.
Accordingly, it was highly desirable to add some type of composition to the blood sample so as to permit a clean and efficient separation of the blood clot material from the blood serum. It was desired that such a composition would allow the blood clot and higher specific gravity material to flow through the composition and settle at the bottom of the sample vessel, and when agitation was terminated that such composition would form an integral layer completely separating the blood serum from the blood clots whereupon the blood serum could be poured off in essentially a pure form free of undesirable materials so that such blood serum could be utilized in medical laboratory analysis. It was also highly desirable that such a composition for separating blood clots from the blood serum does not give off any of its ingredients into the blood serum since such ingredients might deleteriously affect the subsequent medical laboratory analysis.
Accordingly, as stated previously, while various materials were tried for this purpose and specifically ones that had a specific gravity intermediate between the specific gravity of the blood clot and the specific gravity of the blood serum, no composition has hereto been found which has the proper combination of rheological properties and specific gravity properties.
Accordingly, it is one object of the present invention to provide for a silicone composition that has controlled rheological properties and a specific gravity that varies from 1.035 to 1.06.
It is another object of the present invention to provide for a silicone composition with controlled rheological properties and specific gravity that varies from 1.035 to 1.06 which composition is basically inert and nontoxic.
It is an additional object of the present invention to provide for a silicone composition with controlled rheological properties and specific gravity that varies from 1.035 to 1.06 which has very little bleed out of its ingredients under intensive agitation conditions.
It is still another object of the present invention to provide for a silicone composition with controlled rheological properties and specific gravity that varies from 1.035 to 1.06 which is suitable in the separation of blood serum from blood clots in medical laboratory analysis.